1. Field of the Invention
This invention relates generally to medical and surgical devices and more specifically to access seals adapted for use in urological procedures.
2. Discussion of the Relevant Art
There are many procedures which involve the exploration, visualization and manipulation of body conduits such as the vascular system, digestive tract, and urinary tract. Notwithstanding the wide application of the present invention, a more detailed description will be undertaken only with respect to a single field of use.
In the urinary tract it is well known that stones, which commonly form in the kidneys and the bladder, often need to be surgically removed. This procedure is typically undertaken using a ureteroscope having a working channel that is accessible through an exit port. Initially, a guidewire is threaded through the urinary tract, perhaps with the assistance of a cystoscope. Once the guidewire is in place, the ureteroscope can be advanced over the guidewire which is back-loaded into the working channel of the ureteroscope. Once the ureterscope is in place, it is used to visualize the interior of the kidney, for example.
This visualization is enhanced by irrigating the kidney through the ureterscope. This irrigation fluid which is typically introduced to a separate channel in the ureteroscope nevertheless tends to fill the working channel. Within the working channel, the irrigation fluid would flow retrograde through the exit port contaminating the surgical site were it not for a urology seal placed over the exit port. In the past, these urology valves have typically been provided with an elastomeric septum or duckbill having characteristics for forming both a zero seal in the absence of an instrument, such as the guidewire and to form an instrument seal in the presence of the instrument. Both of these valves rely upon force more than compliance for their sealing characteristics. Accordingly, there is significant resistance associated with the introduction and removal of instruments through these urology valves. These valves also accommodate a very limited range of instrument sizes and tend to degrade over a short period of time.